Manufacture of paper for photographic purposes



Sept. 12, 1944. H. R. CLARK 2,358,056

MANUFAGTURE OF PAPER ,FOR PHQTOGRAPHIC PURPOSES Filed July 27, 1940 Y PAPER HALFORD lR. CLARK INVENTQR Patented sept. 12, 1944 fA UNITED STATE s PATENTv OFFICE MANUFACTURE OF PAPER FOR v PHOTOGRAPHIVC PURPOSES I 'Halford Rogers Clark, Rochester. N. Yg, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Y Y vApplication July 27, 1940, SeralNo. 348,013

5 Claims.

This invention relatesto .the manufacture of vpaper for photographic purposes in which barium rial can be controlled by the viscosity ofthe polyvinyl alcohol which is employed and also by the sulfate,` dispersed in polyvinyl alcohol, is emvents the infiltration of a photographic emulsion thereon into the fiber of the paper, on the other handk it protects .the photographic ,emulsion against the action of impurities contained in the paper. Inthe case of photographic emulsions A in which other substances than gelatin are employed as the carrier for the silver halide, baryta coatings consisting of blanc fixe in gelatin have been unsatisfactory due, in many cases, to the sensitizing dyes in such emulsions being drawn down, or bleeding, into the baryta coating.

One object of my invention is to provide a method of -coating paper for photographic purposes with which non-gelatin silver halide photographic emulsions may be used without any bleeding of the sensitizing dye into the coating or the paper. Other objects of my invention will appear herein.

I have found that blanc iixe, dispersed in a water solution of polyvinyl alcohol containing a i plasticizer, is eminently suited for coating paper to prepare it for applying a photographic emulsion thereto. I have found that by so coating paper, non-gelatin photographic emulsions, such as described in Salo Patent No. 2,110,491, Fordyce application Serial No. 221,584, led July 27, 1938, Lowe application Serial No. 318,560, led February l2, 1940, and U. S. Patent No. 2,286,215, will satisfactorily adhere thereto and the sensitizing dyes in those emulsions will not bleed into the baryta coating or the paper. I have found that a baryta coating of barium sulfate, dispersed in polyvinyl alcohol, on paper prevents the inltration of a photographic emulsion thereon into the fiber of the paper and also protects the emulsion against any impurities which might be present in the paper.

The dispersion is prepared by incorporating barium sulfate or blanc Xe into a water solution of polyvinyl alcohol containing plasticizer and this dispersion is spread upon the paper in a thin coating such as by means of a spreading machine. Obviously, other methods of application may be employed if desired, Ysuch as by spraying, etc. The viscosity of the coating matecoatings. Y If desired, however, evengreater pron ratio of blanc fixe to polyvinylV alcohol therein. 'I'he polyvinyl alcohols, havinga viscosity of 2-60 cps., are ordinarily suitable for this purpose.

VThe percentage of solids to liquids in the coating solution may be that which Voperates most satisfactorily. For instance, in some cases, 15% would be satisfactory to one operator, in another case, 9% vwould be satisfactory, while in other cases, .percentages between these limits, or above or below them, might be employed. With the low viscosity polyvinylalcohols, the amount of solventnecessary is lessthan withthe high viscosity polyvinyl alcohols and, therefore, the percentage of solids to liquids will admit of variation over quite a wide range. The percentage of barium sulfate or blanc iixe is that necessary to give a good surface to the paper. The per-v centages of barium sulfate may be those ordinarily employed in the case of gelatin baryta thereon. The applications to paper of a plurality f of coatings of barium Ysulfate dispersed in a water solution of polyvinyl alcohol is also vtorbe understood as within the scopeof my invention.

The accompanying drawing is of a photographic paper in accordance with my invention. Upon the support of paper a layer of baryta coating is deposited, essentially consisting vof baryta or barium sulfate dispersedjin an aqueous solution of polyvinyl alcohol. Upon evaporation of the water, a baryta-coated paper is obtained. The photographic paper is then formed by applying a silver halide photographic emulsion layer thereto in the usual manner.

The following example illustrates the preparation of a baryta coating in. accordance with The material contained 23% solids and 2.3%

dispersion by meansrof the spreading machineV yand after drying, the paper was found to be satisfactory for coating with asilver halide photographic emulsion. Although a gelatin photographic emulsion can be applied to the paper poylvinyl alcohol. Paper Vwas coatedwith this coated with baryta, my inventionl is particularly applicable to the preparation ofphotographic pal pers in which non-gelatin photographic emulsions are coated over the baryta coating.V v Inothe example, a small amount of butyl which might Voccur in running the mixture through a colloid mill to impart homogeneity;l

thereto. Any compatible foaming agent maybe Y yadded if the amount of foaming otherwise present stable and a sharp, clear-cut image may be re'-A Y cordedV thereon.

I claim I. A photographic sisting of barium sulfate dispersed inpolyvinyl alcohol, and an Yovercoatingof a photographic Y paper essentially-consisting of paper having a coating thereon essentially con- `alco-V Y Vhol was incorporated to 1 decrease the foaming consistingnof barium sulfate,- polyvinyl alcohol,

anda small proportion of plasticizei',v and an v Y overcoating of a photographic emulsion essenltially'consisting of silver halide and a carrier therefor selected from the group consisting of gelatin and polyvinyl alcohol, the barium sulfate' coating protecting the emulsion from substances having aderogatory-'efi'ectthereom L3'. A photographicv paper'essen'tially consisting of paperhaving aooating thereon essentially consisting of barium sulfate dispersed in poly-l vinyl alcohol, and an` Vovercoating of a photographic emulsion in Vwhich polyvinyl alcohol is `present as the protective colloid for the silver halide, the. barium .sulfate coating on the paper .protecting .the emulsion from substances having a derogatory effect thereon. 1

,4.Y A photographic paper essentially consisting of paper` having a coating thereon essentially consisting of barium sulfateY dispersed in polyvinyl alcohol and ,an overcoating of a photographicV Y `emulsion essentially consistingof silver halide, a

' carrier therefor essentially consisting of' gelatin emulsion essentially consisting of silver halide Vand ya carrier therefor selected from the groupv consisting of gelatin and polyvinyl alcohol, the bariumV sulfate coating protecting the emulsion f from substances f having aV derogatory effect thereon.A

2. Afphotographic paper essentially consisting of paper having aV coating thereonV essentially 'Y the'prot'ective colloid for the silver'halide, the,

barium :sulfate coating protectingthe emulsion from substances [having a derogatoryfefleci;V

and a polyvinyl alcohol and'afsensitizingldye. the barium sulfate coating preventing the'passage of discoloring materials from one outer layer tothel other. Y v o l l i5. A photographic palperv essentially consisting of paper having `a Vcoating thereon, essentially consisting of barium sulfate' dispersed in polyvinyl ValcoholV and an' overcoating 'of a photo'- graphic emulsion in which gelatin is present as thereon. Y HALFORD R. CLARK. 

